Froth flotation



Patented Nov. 17, 1942 FROTH FLOTATION August Moeller and Ernst Wagner, Frankfort-onthe-Main-Griesheim, Germany; vested in the Allen Property Custodian No Drawing. Application May 11, 1939, Serial No. 273,144. In Germany May 18, 1938 2 Claims. (Cl- 209-166) The present invention relates to froth flotation.

If sparingly soluble reagents are used in flotation processes they can rapidly and extensively be distributed in the pulp or sludge only with difliculty. It has hitherto been necessary to add said substances already in the mill and to put up with the difliculties connected therewith in the screening, such as a premature foaming or the like; the eflicacy of the substances however could not be entirely utilized thereby.

Attempts have, therefore, been made to emulsify the reagents (see W. Peterson, Metall und Erz," vol. 34, 1937, p ge 367). As the usual emulsifying agents, such as soaps and wetting agents, may have a disturbing action on the flotation process, by either decreasing the effect of the collector or by having a collecting action on the gangue (for instance in the case of sulphidic ores) and as furthermore a relatively large quantity of the emulsifying agent is required, which has a detrimental action upon the formation of froth and makes its application expensive, such a method of operatingv has not been found useful for industrial purposes.

Further attempts have been made to add the sparingly soluble or insoluble reagents in the form of alcoholic solutions to the sludge or to emulsify them by the treatment with ultra sound waves. As in the first named casea multipl quantity of alcohol calculated upon the quantity of the reagent has to be added, and as in the last named case a complicated apparatus showing the inferior effect has been necessary, both processes have likewise not been applied for industrial purposes.

Now we have found that oil-solubl emulsifying agents of the kind of the reaction products of alkylene oxides on aliphatic or aromatic compounds containing hydroxyl-, carboxylor aminogroups do not disturb the flotation and maintain their emulsifying action even if the usual reagents at best sparingly soluble in water and admixed.

with only a small quantity of these bodies are added to the sludge in the usual proportions. The said emulsifying agents are characterized by the eneral formula wherein R stands for a member of the group consisting of alkyl, aryl, aralkyl and hydroaromatic groups, X stands for a member of the group consisting of NH, O and COO, n is a whole number greater than 1 and m is a whole number, i. e., they contain a number of alkylene oxide groups in an ether-like chain. As the emulsifying agents named are readily soluble in water and as the flotation substance is added to th sludge in a proportion of 1:4000 to 1:40.000, 1. e., 100,000 to 1 million parts and more of water are used for 1 part of emulsifying substance, it is surprising that the emulsifying effect is maintained in spite Of the high dilution.

In view of these two facts it is possible to carry out the flotation in a simple manner by means of very sparingly soluble or insoluble reagents by mixing the reagent in question with the small quantity of emulsifying agent required (for instance 2 to 5 per cent) and adding the mixture to the pulp directly before it is or after it has been introduced into the flotation 'vessel. The insoluble reagent distributes at once just as a watersoluble substance and is completely effective. Owing to the improved distribution the sparingly soluble or insoluble reagents may rapidly and readily reach the places where they have to be effective. By the application of a reagent thus emulsified the flotation is simplified and acceler ated and owing to the better utilization a large quantity of reagents can be saved.

The floating agents according to the invention may be used for all non-metallic minerals, particularly the so-called oxidic and sulphidic ores, for instance phosphorite, apatite, fluorite, tungstite, scheelite, chromite, native tin, calcite, heavy spar, as well as the oxides, carbonates, sulfides or the like of the heavy metals, and others.

The following examples serve to illustrate the invention, but they are not intended to limit it thereto:

1. Fluorspar (fluorite) from the mountains Hartz (Germanv) containing 82.8 per cent. of CaFz, 11.8 per cent. of SiO: and 3.5 per cent. of Fe2O3+A12O3 and comminuted to a granular size of 61.8 per cent. smaller than 0.06 millimeter is worked up (a) with 450 grams per ton of oleic acid containing 5 per cent of higher hydroxyethylated castor oil (with 40 hydroxy-ethyl groups), (b) only with 450 grams per ton of oleic acid as a collector.

Proportion of the pulp: 1:5; reaction period: 5 minutes.

(b) Oleic acid without emulsifying agent Per cent Per cent Yield of Product by weight of CaF; Cal",

2. A lead-zinc ore originated from the mine Hiils" (Westphalia, Germany) containing about 7 per cent. of Pb and comminuted to a granular size of v71.9 per cent smaller than 0.076 millimeter is worked up (a) with 45 grams per ton of ethyldixanthogene containing per cent. of higher hydroxyethylated castor 011 (1)) only with 45 grams per ton of ethyldixanthogene as a collector. The reaction period amounts to 5 minutes in each case.

Addition of frothing agent: 30 parts by weight of a usual frothing substance, for instance pine oil or terpene alcohol.

For depressing the zinc blende (sphalerite) there are added:

Grams NaCN per t -200 ZnSOr per ton 200 Sodium carbonate per ton 500 G110 per ton 800 Proportion of the pulp: 1:3.5. Temperature of the pulp: 20 C. Flotation period: 15 minutes. After activation of the zinc blende it can be floated out with (a), but not with (b). As a standard of comparison does not exist, the zinc is not valued. As regards the lead the following figures are obtained:

Instead of the castor oil hydroxy-ethylated with 40 mol of ethylene oxide there may be used lower hydroxy-alkylated products for the purposes in question, for instance the reaction products with only 20 or mol of ethylene oxide. As emulsifying agents there are furthermore suitable higher hydroxy-ethylated sperm oil alcohols, hydroxy-ethylated oleylamlne with 10 mol of ethylene oxide, higher hydroxy-ethylated alkylated phenols for instance with 20 to mol of ethylene oxide or the like. The addition of sulphonated castor oil in froth flotation is known, but this is not the object of the present invention.

We claim:

1. In a method of froth flotation, the step of agitating and aerating a pulp of an ore in the presence of oleic acid and a higher hydroxyethylated castor oil obtained by the addition of 40 mols of ethylene oxide to one mol of castor 0 oil.

castor oil. I

AUGUST MOELIER. ERNST WAGNER.

CERTIFICATE OF CORRECTION. Patent- No. 2, 02, 58. Novem'ber 17, 191 2. AUGUST MOELLER, ET AL.

It is hereby certified that error appears 1n the printed specification ofthe'abo've numbered patent requiring correction as follows: Page 2 0nd column, line 26, claim 1; for the words- "an ore" read -'-a non-metallic ore--; line 56, claim 2, after f'oil. insert the-following claim sec- 5. In a method of froth flotation, the step of agitating and aerating a pulp of a non-metallic ore in the presence of oleic acid' and a higher hydroxiethylated castor oil obtained by the addition of from 20 to 1+0 mole of ethylene oxide to one mol of castor oil.

in the heading to the printed specification, line 8, for "2 Claims read "5 Claims--; and that the said Letters Patent should be read with this correction therein that the same 'may conform to the record gf the case in the Patent Office.

Signed and sealed this 15th day of August, A. D. 19bit.

Leslie Frazer (Seal) Acting Commissioner of Patents. 

